The batteries are charged at a current equivalent to 0.1 times the capacity expressed in Ampere hours (Ah) for a maximum of 15 hours. (12 - 13 hours would normally be sufficient with a constant current charger, but 15 hours may be necessary with a taper charger.) The duration of the recharge will depend on the extent of the discharge that the battery has experienced. As an example the 60 Ah type RR1 battery that has been utilized for 3 hours for lighting a 100W lamp would have consumed 24.9 Ah and therefore must be charged at 5 Ampere for approximately 6 hours.